METHOD FOR MONITORING SHORT-CIRCUIT SWITCHING OPERATIONS IN A CIRCUIT OF A CONTROL UNIT

Description

[0001] The present invention relates to a method for monitoring short-circuit switching operations of a circuit of a control unit, in particular in a vehicle, and a computing unit for carrying out the method. Background of the invention

[0002] Power amplifiers or power amplifier circuits in control units, for example in (motor) vehicles, represent the final electronic stage of a power amplifier before an amplified signal is applied to a load. For example, power amplifier circuits can be provided in an engine control unit to provide the power required to control actuators. In the control unit, the respective power amplifier circuits can be controlled by a microcontroller using appropriate control signals.

[0003] To ensure the (operational) safety of the control unit, the power amplifier circuits should generally be robust enough to withstand at least a specified minimum number of switching operations in the event of a short circuit, i.e., a short circuit to the battery or ground. However, if an excessive number of such short-circuit switching operations are performed, especially with PWM control, this can result in damage or even destruction of the power amplifier and thus the entire control unit.

[0004] A method for monitoring switching operations in a circuit is known from published patent application CN 107 976 626 A. In particular, it is intended to determine the service life of a relay. For this purpose, a relay service life detection device is provided, which comprises a control unit, an on / off counter unit, a human-machine interface unit, a relay control unit, and an oscillator unit. The human-machine interface unit indicates the service life of the relay switches. Disclosure of the invention

[0005] Against this background, a method for monitoring short-circuit switching operations in a control unit circuit and a computing unit for implementing the method are proposed, having the features of the independent patent claims. Advantageous embodiments are the subject of the dependent claims and the following description.

[0006] In the course of this method, current information regarding the control unit is recorded and evaluated to determine whether a short-circuit switching operation is occurring, i.e., whether the circuit is performing a switch-on operation during a short circuit (i.e., without load). If, during the course of the evaluation, it is detected that a short-circuit switching operation is occurring, a counter or counter value is updated or incremented, which characterizes or represents the number of short-circuit switching operations performed over the circuit's lifetime.

[0007] By capturing and evaluating control unit information, it is possible to conveniently detect whether a short-circuit switching operation is currently occurring during the control unit's operation. The counter reading is thus continuously updated throughout its service life whenever a new short-circuit switching operation is detected.

[0008] Based on the counter reading, measures can be taken to protect the power amplifier circuit or to correct errors. Furthermore, the counter reading allows conclusions to be drawn about the risk of damage or destruction to the power amplifier. Furthermore, operation of the power amplifier can be restricted or influenced if the counter reading is very high and, for example, approaches a specified number of permitted switching operations in the event of a short circuit.

[0009] The odometer reading can be conveniently read in a workshop and can, for example, facilitate troubleshooting or repairs. Furthermore, in the event of damage to or destruction of the power amplifier or control unit, the odometer reading can be helpful in subsequently determining the cause. The odometer reading is particularly useful for checking whether a warranty claim is justified. For example, the odometer reading can be used to determine whether an (end) customer has ignored a warning message, such as an activated check engine light, for an extended period of time, which could lead to a reduction or exclusion of warranty coverage by the (control unit) manufacturer.

[0010] The information relating to the control unit particularly characterizes the current operation of the control unit, in particular current signals from the control unit for controlling the power amplifier circuit, and also in particular current errors or error messages from the control unit. This information can be used to particularly usefully determine whether the circuit is currently being controlled and whether a short circuit is currently present in the control unit. For example, various measures for short-circuit detection in the power amplifiers of vehicle control units are known and in some cases even prescribed. For example, recorded measured values can be evaluated. For example, it can be checked whether a current through the power amplifier circuit exceeds a permissible limit. Furthermore, error diagnostics or diagnostic functions of the control unit can be used to detect error states.

[0011] Advantageously, depending on the counter reading or a current value of the counter reading, a prioritization of short-circuit switching operations is carried out that are or should or may be carried out during a specified diagnostic interval, in particular during a current diagnostic interval. For example, these individual diagnostic intervals can each correspond to a driving cycle of the (motor) vehicle. Short-circuit switching operations that are carried out as part of a fault diagnosis or fault detection are expediently prioritized. Based on such switching operations for fault diagnosis, it can be checked or detected in particular whether the short circuit is still present or whether the control unit is functioning correctly without a short circuit after being cured. With the help of this prioritization, it can be expediently set or specified how often a check is carried out per diagnostic interval to determine whether the short circuit is still present.The higher the assigned priority, the more frequently a fault diagnosis is performed per diagnostic interval. In particular, as the circuit's lifetime increases, the number of fault diagnoses performed per diagnostic interval can be continuously reduced to avoid unnecessary short-circuit switching operations and damage to or destruction of the power amplifier circuit.

[0012] For example, if the counter reading is low, which particularly reflects the beginning of the power amplifier's service life, fault diagnosis or fault detection can be given a higher priority than if the counter reading is higher during a later phase of the power amplifier's service life, because the chances of healing or eliminating the short circuit are greater at the beginning of the service life than towards the end of the service life. For example, by assigning a high priority when the counter reading is low, it is possible to check several times per diagnostic interval whether the short circuit is still present. If the counter reading is higher, a lower priority can be assigned, in particular fewer or no switching operations for fault diagnosis per diagnostic interval in order to avoid unnecessary loads or even a defect in the power amplifier circuit.For example, a switching operation for fault diagnosis can be assigned a high or highest priority if the counter reading is below a specified limit. The closer the counter reading approaches this limit, the lower the priority can be selected.

[0013] Traditionally, the number of short-circuit switching operations performed per diagnostic interval is limited to a predefined maximum number, depending, for example, on the type of power amplifier, the power supply, the system used, the configuration, the sensors used, the current ambient temperature, etc. Traditionally, when a short circuit is detected, an error notification is issued, particularly by activating an engine control lamp. Further checks are performed at predefined intervals during a diagnostic interval to determine whether the short circuit is still present, up to the predefined maximum number of short-circuit switching operations per diagnostic interval. If the short circuit has not been resolved by then, a corresponding function of the control unit is often permanently deactivated for the remainder of the diagnostic interval.Even if the short circuit is cured during this diagnostic interval, this can no longer be detected, and the corresponding function remains deactivated. The short circuit may only be checked again in a subsequent diagnostic interval.

[0014] In contrast, the counter reading in this method can be used to dynamically adjust how often errors are checked per diagnostic interval, particularly based on the lifetime. Since a cure is more likely at the beginning of the lifetime than with a long lifetime, checks are performed more frequently so that any cure of the short circuit can be detected and control unit functions are not unnecessarily deactivated across the board, even though a short circuit may no longer exist. With a long lifetime, errors can then only be checked rarely or not at all per diagnostic interval, since a cure is less likely here, but the risk of destroying the power amplifier circuit is increased.

[0015] Preferably, a limit is set for the number of short-circuit switching operations that are, should, or may be performed during a diagnostic interval or a driving cycle, in particular during a current diagnostic interval or driving cycle, as a function of the counter reading or a current value of the counter reading. As explained above, short-circuit switching operations for fault diagnosis can often be limited to a static, fixed value per diagnostic interval in a conventional manner. In contrast, by introducing the counter reading, it is particularly expedient to limit the number of permitted short-circuit switching operations per diagnostic interval dynamically over the service life of the circuit, in particular dynamically adapted to the number of short-circuit switching operations that the circuit has already performed during its previous service life.

[0016] According to a preferred embodiment, the counter reading or the current value of the counter reading is compared with a predetermined threshold value. For example, this threshold value can be predetermined depending on a minimum number of short-circuit switching operations which the power amplifier circuit must at least withstand during its service life. The threshold value can, for example, represent that the number of short-circuit switching operations carried out so far is increasingly approaching this minimum number, so that there is an increasing risk of damage to the circuit. If the threshold value is reached or exceeded, further switching operations can in particular be prevented or prohibited. Preferably, the prioritization of the short-circuit switching operations is carried out and / or the number of short-circuit switching operations is limited depending on the comparison of the current counter reading value with the predetermined threshold value.In particular, there is no blanket, static limitation of switching operations per diagnostic interval, but rather it can be dynamically adjusted which or how many switching operations are permitted in the event of a short circuit, expediently depending on the current lifetime of the power amplifier circuit.

[0017] In particular, as explained above, a maximum value can be specified as a threshold value for a number of short-circuit switching operations that may be carried out during a diagnostic interval.

[0018] Particularly preferably, the threshold value is specified depending on the number of diagnostic intervals performed. The threshold value is thus expediently adjusted dynamically depending on the previous service life of the power amplifier circuit.

[0019] Advantageously, the threshold value, particularly for a current diagnostic interval, is specified depending on a (e.g., linear or logarithmic) relationship between a number of permitted short-circuit switching operations and one of the previously performed diagnostic intervals. Using a logarithmic relationship, a high number of short-circuit switching operations can be permitted per diagnostic interval, particularly at the beginning of the power stage's service life. As the minimum number of short-circuit switching operations that the power stage circuit must withstand during its service life approaches, increasingly fewer short-circuit switching operations can be permitted per diagnostic interval.

[0020] The threshold value, in particular for a current diagnostic interval, is expediently specified as a function of a maximum value for the number of short-circuit switching operations that may be performed during the service life of the circuit, and in particular as a function of a distance between a number of short-circuit switching operations and the maximum value for the number of short-circuit switching operations that may be performed during the service life of the circuit. Such a relationship can allow a high number of short-circuit switching operations per diagnostic interval, particularly when the distance from the maximum value is large. As the maximum value is approached, increasingly fewer short-circuit switching operations are permitted per diagnostic interval in order to protect the circuit.

[0021] Preferably, the counter reading is only incremented if it is detected during the evaluation that a high-side switch in the circuit is switching on during a short circuit to ground and / or that a low-side switch in the circuit is switching on during a short circuit to the supply voltage. In the case of power amplifiers installed on the ground side or in the case of low-side switches that are connected to ground by a terminal or in which the load is arranged between the switch and the supply voltage, switch-on pulses in particular can have a damaging effect on the circuit in the event of a short circuit to the supply voltage, so that in this case it is particularly expedient to document switching operations during such a short circuit with the counter reading. In the case of power amplifiers installed on the voltage side, i.e. in the case of high-side switches that are connected to the supply voltage by a terminal orIn the case of a load arranged between the switch and ground, switch-on pulses in the event of short circuits to ground can, however, have a damaging effect, so that in this case switching operations in the event of short circuits to ground are expediently counted using the counter reading.

[0022] A computing unit according to the invention, e.g. a control unit of a (motor) vehicle, is configured, in particular in terms of programming, to carry out a method according to the invention.

[0023] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0024] The invention is illustrated schematically in the drawing using exemplary embodiments and is described below with reference to the drawing. Short description of the drawings

[0025] Figure 1 schematically shows a control unit with an output stage circuit, which is configured to carry out a preferred embodiment of a method according to the invention. Figure 2 schematically shows a preferred embodiment of a method according to the invention as a block diagram. Figure 3 schematically shows a diagram of a number of permitted short-circuit switching operations plotted against a number of performed driving cycles, which can be determined in the course of a preferred embodiment of a method according to the invention. Embodiment(s) of the invention

[0026] In Figure 1 A control unit of a (motor) vehicle is shown schematically and designated 100.

[0027] The control unit 100 can be provided, for example, as an engine control unit for controlling an internal combustion engine 130 and has a microcontroller 110 and a semiconductor output stage circuit 120, for example in the form of a MOSFET bridge circuit with high-side switches and / or low-side switches. Using appropriate control pulses, the microcontroller 110 can control these semiconductor switching elements of the output stage circuit 120.

[0028] The power amplifier 120 is designed to withstand a minimum number of short-circuit switching operations without damage. Exceeding this number of short-circuit switching operations may increase the risk of damage or even destruction to the power amplifier 120 and the control unit 100.

[0029] In order to prevent this danger, the control unit 100 is set up, in particular in terms of programming, to carry out a preferred embodiment of a method according to the invention, which is shown schematically in Figure 2 is shown as a block diagram and will be explained below.

[0030] In a step 201, the control unit 100 or the corresponding (motor) vehicle is operated normally. In step 202, information relating to the control unit 100 is acquired, in particular information characterizing the current operation of the control unit. In particular, this information relates to current signals or control pulses from the microcontroller 110 for controlling the output stage circuit 120, as well as current errors present in the control unit 100. For example, a duty cycle of a control signal of semiconductor switching elements, currents through semiconductor switching elements, error memory information, or entries in an error memory are acquired as this information.

[0031] In a step 203, this information is evaluated to determine whether a short-circuit switching operation is present, i.e. whether a control pulse or a (switching-on) pulse is output by the microcontroller 110 to the output stage circuit 120 while an error condition in the form of a short circuit exists in the output stage circuit 120, in particular whether a high-side switch of the output stage circuit 120 is thus carrying out a switching-on operation against ground and / or whether a low-side switch is carrying out a switching-on operation against the supply voltage (e.g. battery).

[0032] As long as this is not the case and no such short-circuit switching process occurs, the information relating to the control unit continues to be recorded in step 202 and evaluated in step 203.

[0033] If, however, it is detected in step 203 that such a short-circuit switching operation has occurred, a counter reading is updated or incremented in step 204, which characterizes the number of short-circuit switching operations performed over the service life of the power amplifier circuit 120. The current value of this counter reading thus corresponds to the number of all short-circuit switching operations that the power amplifier circuit 120 has performed since the beginning of its service life or since its initial commissioning in the control unit 100.

[0034] This counter reading can be read, for example, in a workshop and used for troubleshooting, repairs, or verifying a warranty claim. For example, the counter reading can be used to determine whether a vehicle driver has ignored a warning message, such as an activated check engine light, for an extended period of time, which could lead to a reduction or exclusion of a warranty from the manufacturer of the control unit 100.

[0035] In step 205, the counter reading or the current value of the counter reading is compared with a threshold value, in particular with a maximum value for the number of short-circuit switching operations that may be carried out during a diagnostic interval or a driving cycle for fault diagnosis.

[0036] Conventionally, the number of permitted short-circuit switching operations per diagnostic interval is often statically limited to a constant, fixed value. The introduction of the current counter reading, however, allows the permitted short-circuit switching operations per diagnostic interval to be flexibly and dynamically adjusted, depending on the number of short-circuit switching operations that the circuit 120 has already performed during its lifetime.

[0037] The threshold value is specified, in particular, depending on the number of diagnostic intervals that the power amplifier circuit 120 or the vehicle has already performed. For example, in early phases at the beginning of the service life of the power amplifier circuit 120, a higher number of short-circuit switching operations per diagnostic interval may be permitted than in later phases, since there is a greater chance of healing the short circuit at the beginning of the service life. In particular, the threshold value for the current diagnostic interval is specified depending on a linear or logarithmic relationship between the number of permitted short-circuit switching operations and the number of performed diagnostic intervals.

[0038] Based on the threshold value comparison 205, the number of short-circuit switching operations that may still be performed in the current diagnostic interval for fault diagnosis is limited in step 206. Furthermore, a prioritization of individual short-circuit switching operations can be performed in step 206 based on the comparison result. For example, at the beginning of the service life of the circuit, 120 short-circuit switching operations can be assigned a higher or highest priority during the fault diagnosis, and a high or even unlimited number of such switching operations for misdiagnosis can be permitted per diagnostic interval, since in this case there is a high chance of a cure or successful fault rectification.At later stages of the service life, after a high number of diagnostic intervals have been performed, the priority of such short-circuit switching operations for fault diagnosis can, for example, be selected to be lower and, for example, only one attempt or one switching operation for fault diagnosis can be specified in order to avoid possible damage or destruction of the control unit 100.

[0039] In Figure 3 A diagram of the number m of permitted short-circuit switching operations plotted against the number n of performed diagnostic intervals is shown schematically.

[0040] Curve 310 represents a corresponding linear relationship and curve 320 a corresponding logarithmic relationship, depending on which the threshold value for the current diagnostic interval can be specified in step 205.

[0041] M denotes a minimum number of short-circuit switching operations which the power amplifier circuit 120 must at least withstand during its service life.

[0042] For example, 315 denotes the number of permitted short-circuit switching operations for the diagnostic interval N1 according to the linear relationship 310, and 325 denotes the number of permitted short-circuit switching operations for the diagnostic interval N1 according to the logarithmic relationship 320.

[0043] According to the logarithmic relationship 320, more short-circuit switching operations are permitted per diagnostic interval, particularly at the beginning of the service life of the circuit 120, than according to the linear relationship 310. Furthermore, according to the logarithmic relationship 320, fewer and fewer short-circuit switching operations are permitted per diagnostic interval as the minimum number M is increasingly approached.

[0044] For example, starting from the logarithmic relationship 320, the number of permitted short-circuit switching operations per diagnostic interval can be determined online during the current diagnostic interval by means of a Taylor expansion.

[0045] A qualitatively similar curve results if the threshold is specified as a function of the distance between the number of short-circuit switching operations and the maximum value for the number of short-circuit switching operations that may be performed during the circuit's lifetime. This allows a high number of short-circuit switching operations per diagnostic interval to be permitted, especially at a large distance from the maximum value. As the maximum value is approached, increasingly fewer short-circuit switching operations are permitted per diagnostic interval to protect the circuit.

Claims

1. Method for monitoring short-circuit switching operations of a circuit (120), in particular an output stage circuit (120) of a control device (100), characterized in that information relating to a control device (100) is captured (202) and evaluated (203) in order to determine whether there is a short-circuit switching operation present, wherein the circuit (120) carries out a switch-on operation during a short circuit, and wherein, if, in the course of the evaluation, it is detected that a short-circuit switching operation is present, a counter reading that characterizes a number of short-circuit switching operations carried out over a service life of the circuit (120) is updated (204).

2. Method according to Claim 1, wherein short-circuit switching operations that are carried out during a diagnostic interval, in particular short-circuit switching operations that are carried out in the course of a fault diagnosis, are prioritized or limited depending on the counter reading (206).

3. Method according to Claim 1 or 2, wherein the counter reading is compared with a predetermined threshold value (205), in particular with a predetermined maximum value for a number of short-circuit switching operations that may be carried out during a diagnostic interval.

4. Method according to Claim 3, wherein the threshold value is predetermined depending on a number of diagnostic intervals.

5. Method according to Claim 4, wherein the threshold value is predetermined depending on a relationship (310) between a number of short-circuit switching operations (m) and the number of diagnostic intervals (n).

6. Method according to one of Claims 3 to 5, wherein the threshold value is predetermined depending on a maximum value for a number of short-circuit switching operations that may be carried out during the service life of the circuit (120).

7. Method according to Claim 6, wherein the threshold value is predetermined depending on a difference between a number of short-circuit switching operations (m) and the maximum value for a number of short-circuit switching operations that may be carried out during the service life of the circuit (120).

8. Method according to one of Claims 3 to 7, wherein short-circuit switching operations are prioritized (206) and / or the number of short-circuit switching operations is limited (206) depending on the comparison (205).

9. Method according to one of the preceding claims, wherein the counter reading is updated (204) if, in the course of the evaluation, it is detected that a high-side switch of the circuit (120) carries out a switch-on operation during a short circuit to ground and / or that a low-side switch of the circuit (120) carries out a switch-on operation during a short circuit to battery.

10. Computing unit (100), which is designed to carry out all of the method steps of a method according to one of the preceding claims.